I've been stalled on moving to cast bullets. Could use a little help here. I've slugged the barrel of my Krag from the muzzle and driven the slug all the way through. Slugs at .308. I was thinking of ordering bullets sized to .309. But I've been reading that a better indicator for bullet size is gotten from slugging just ahead of the throat. Is that what folks have done here?

When playing with a new rifle I pour a chamber cast that includes an inch or so in front of the chamber, in addition to slugging the bore. If your bore mic's at .308, I would try the .309's, and be prepared to try some at .310 and .311 too. Most of my .30's respond well to .310 diameter so that is what I usually start with, and .311 for plain based soft lead bullets at low velocity.

I slugged the throat on my Krag today. Here are my dimensions: Throat/Free Bore - .314, beginning of rifling - .309, a couple of inches down from the muzzle - .308

I've been neck resizing with a Hornady all purpose 30 cal neck resized for jacketed bullets that measure .308. What do I do for cast, particularly if the bullet I use is sized for the throat (.314)?

Thomassen wrote on Feb 25^th, 2013 at 1:02am:

What do I do for cast, particularly if the bullet I use is sized for the throat (.314)?

Obtain a Lyman M-die (size 31-L) to expand the neck appropriately.   (You need to Login

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That'll do it. Thanks.